1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * SUCS NET3:
4 *
5 * Generic stream handling routines. These are generic for most
6 * protocols. Even IP. Tonight 8-).
7 * This is used because TCP, LLC (others too) layer all have mostly
8 * identical sendmsg() and recvmsg() code.
9 * So we (will) share it here.
10 *
11 * Authors: Arnaldo Carvalho de Melo <acme@conectiva.com.br>
12 * (from old tcp.c code)
13 * Alan Cox <alan@lxorguk.ukuu.org.uk> (Borrowed comments 8-))
14 */
15
16 #include <linux/module.h>
17 #include <linux/sched/signal.h>
18 #include <linux/net.h>
19 #include <linux/signal.h>
20 #include <linux/tcp.h>
21 #include <linux/wait.h>
22 #include <net/sock.h>
23
24 /**
25 * sk_stream_write_space - stream socket write_space callback.
26 * @sk: socket
27 *
28 * FIXME: write proper description
29 */
30 void sk_stream_write_space(struct sock *sk)
31 {
32 struct socket *sock = sk->sk_socket;
33 struct socket_wq *wq;
34
35 if (__sk_stream_is_writeable(sk, 1) && sock) {
36 clear_bit(SOCK_NOSPACE, &sock->flags);
37
38 rcu_read_lock();
39 wq = rcu_dereference(sk->sk_wq);
40 if (skwq_has_sleeper(wq))
41 wake_up_interruptible_poll(&wq->wait, EPOLLOUT |
42 EPOLLWRNORM | EPOLLWRBAND);
43 if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
44 sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT);
45 rcu_read_unlock();
46 }
47 }
48
49 /**
50 * sk_stream_wait_connect - Wait for a socket to get into the connected state
51 * @sk: sock to wait on
52 * @timeo_p: for how long to wait
53 *
54 * Must be called with the socket locked.
55 */
56 int sk_stream_wait_connect(struct sock *sk, long *timeo_p)
57 {
58 DEFINE_WAIT_FUNC(wait, woken_wake_function);
59 struct task_struct *tsk = current;
60 int done;
61
62 do {
63 int err = sock_error(sk);
64 if (err)
65 return err;
66 if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV))
67 return -EPIPE;
68 if (!*timeo_p)
69 return -EAGAIN;
70 if (signal_pending(tsk))
71 return sock_intr_errno(*timeo_p);
72
73 add_wait_queue(sk_sleep(sk), &wait);
74 sk->sk_write_pending++;
75 done = sk_wait_event(sk, timeo_p,
76 !READ_ONCE(sk->sk_err) &&
77 !((1 << READ_ONCE(sk->sk_state)) &
78 ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)), &wait);
79 remove_wait_queue(sk_sleep(sk), &wait);
80 sk->sk_write_pending--;
81 } while (!done);
82 return done < 0 ? done : 0;
83 }
84 EXPORT_SYMBOL(sk_stream_wait_connect);
85
86 /**
87 * sk_stream_closing - Return 1 if we still have things to send in our buffers.
88 * @sk: socket to verify
89 */
90 static int sk_stream_closing(const struct sock *sk)
91 {
92 return (1 << READ_ONCE(sk->sk_state)) &
93 (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK);
94 }
95
96 void sk_stream_wait_close(struct sock *sk, long timeout)
97 {
98 if (timeout) {
99 DEFINE_WAIT_FUNC(wait, woken_wake_function);
100
101 add_wait_queue(sk_sleep(sk), &wait);
102
103 do {
104 if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk), &wait))
105 break;
106 } while (!signal_pending(current) && timeout);
107
108 remove_wait_queue(sk_sleep(sk), &wait);
109 }
110 }
111 EXPORT_SYMBOL(sk_stream_wait_close);
112
113 /**
114 * sk_stream_wait_memory - Wait for more memory for a socket
115 * @sk: socket to wait for memory
116 * @timeo_p: for how long
117 */
118 int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
119 {
120 int ret, err = 0;
121 long vm_wait = 0;
122 long current_timeo = *timeo_p;
123 DEFINE_WAIT_FUNC(wait, woken_wake_function);
124
125 if (sk_stream_memory_free(sk))
126 current_timeo = vm_wait = get_random_u32_below(HZ / 5) + 2;
127
128 add_wait_queue(sk_sleep(sk), &wait);
129
130 while (1) {
131 sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
132
133 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
134 goto do_error;
135 if (!*timeo_p)
136 goto do_eagain;
137 if (signal_pending(current))
138 goto do_interrupted;
139 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
140 if (sk_stream_memory_free(sk) && !vm_wait)
141 break;
142
143 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
144 sk->sk_write_pending++;
145 ret = sk_wait_event(sk, ¤t_timeo, READ_ONCE(sk->sk_err) ||
146 (READ_ONCE(sk->sk_shutdown) & SEND_SHUTDOWN) ||
147 (sk_stream_memory_free(sk) && !vm_wait),
148 &wait);
149 sk->sk_write_pending--;
150 if (ret < 0)
151 goto do_error;
152
153 if (vm_wait) {
154 vm_wait -= current_timeo;
155 current_timeo = *timeo_p;
156 if (current_timeo != MAX_SCHEDULE_TIMEOUT &&
157 (current_timeo -= vm_wait) < 0)
158 current_timeo = 0;
159 vm_wait = 0;
160 }
161 *timeo_p = current_timeo;
162 }
163 out:
164 if (!sock_flag(sk, SOCK_DEAD))
165 remove_wait_queue(sk_sleep(sk), &wait);
166 return err;
167
168 do_error:
169 err = -EPIPE;
170 goto out;
171 do_eagain:
172 /* Make sure that whenever EAGAIN is returned, EPOLLOUT event can
173 * be generated later.
174 * When TCP receives ACK packets that make room, tcp_check_space()
175 * only calls tcp_new_space() if SOCK_NOSPACE is set.
176 */
177 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
178 err = -EAGAIN;
179 goto out;
180 do_interrupted:
181 err = sock_intr_errno(*timeo_p);
182 goto out;
183 }
184 EXPORT_SYMBOL(sk_stream_wait_memory);
185
186 int sk_stream_error(struct sock *sk, int flags, int err)
187 {
188 if (err == -EPIPE)
189 err = sock_error(sk) ? : -EPIPE;
190 if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
191 send_sig(SIGPIPE, current, 0);
192 return err;
193 }
194 EXPORT_SYMBOL(sk_stream_error);
195
196 void sk_stream_kill_queues(struct sock *sk)
197 {
198 /* First the read buffer. */
199 __skb_queue_purge(&sk->sk_receive_queue);
200
201 /* Next, the error queue.
202 * We need to use queue lock, because other threads might
203 * add packets to the queue without socket lock being held.
204 */
205 skb_queue_purge(&sk->sk_error_queue);
206
207 /* Next, the write queue. */
208 WARN_ON_ONCE(!skb_queue_empty(&sk->sk_write_queue));
209
210 /* Account for returned memory. */
211 sk_mem_reclaim_final(sk);
212
213 WARN_ON_ONCE(sk->sk_wmem_queued);
214
215 /* It is _impossible_ for the backlog to contain anything
216 * when we get here. All user references to this socket
217 * have gone away, only the net layer knows can touch it.
218 */
219 }
220 EXPORT_SYMBOL(sk_stream_kill_queues);
221
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